Alkylation process



M-ay 14, 1946. K, OPRYSHEK ETAL 2,400,367

ALKYLATION PROCESS Filed Aug. 2,@1941 Patented: 14, 1946 2,400,367vv lUNIT-so STATES 'PATENTL OFFICE ALKYLATION PROCESS Karl Opryshek and JolmN. Chatiield, Baytown,

Tex., assignors to Standard Oil Development' Company, a corporation ofDelaware Application August-2, 1941, Serial No. 405,128

' 3 claims. (ci. 26o-683.4)

The present invention is concerned with the production of normallyliquid Asaturatedy hydrocarbons suitable for use as motor fuels by aprocess which involves the condensation of isoparaffinie, hydrocarbonswith olen hydrocarbons in the presence of' a`suitable catalyst. Inaccordance with the present invention, the acid emulsion for recyclingand the'acid emulsion for ref covery of the alkylate are withdrawn asseparate' streams from the reaction zone.

It is known in 'the Aart that' saturated hydrocarbons containing atertiary carbon atom, hereinafter referred to as tertiary hydrocarbons,will react with olens in the presence of a suitable catalystsuch asconcentrated mineral acids, re-

sulting in the production of a wide range of higher boiling hydrocarbonproducts. The naleast one tertiary carbon atom per molecule. Theolenicreactants generally 'comprise propylene, Anormal butylenes, isobutylene,trimethyl ethylene, 'the isomeric pentenes and similar highermonooleiinic hydrocarbons of either a straight chain or branched chainstructure. Mixtures of two or more of these mono-olefins are likewiseemployed. Operations are conducted in which the feed ma.-

terial comprises particular refinery butane cuts segregated from variouscracking and distillation operations, such as propane, butane andpentane cuts which comprise constituents boiling in the respectiveboiling ranges. OtherLfeed materials may comprise various polymers,copolymers, interpolymers, and crosspolymers of the above mentionedolefins, such products being, for example, diisobutylene,v'triisobuty1ene, tetraisobutyleneI the codimer, cotrimer andcotetrarner of normal butylenes and isobutylene, the interdixner,intertrimer and intertetramer of isobutylene with pentenes. Y l

The catalyst generally employed comprises a concentrated mineral acidas, for example. a sulfurie acid, a halogenated sulfuric acid,A an acidof phosphorus. 'or an equivalent acid. Other catalysts utilized are asaturated aqueous solution of boron iiuo'ride, the 'metal halides, suchas aluminum halide and iron halide, acid activated clays, as well as themineral acids, employed in commotion with various compounds of the'FifthGroup of the Periodic System, the aluminum halide-alkali metal halidedouble salt complexes,

and various other similar catalysts. When a mineral acid is utilizedasthe catalyst, the acid 5 concentration is above about 80%, preferably inthe range from about 90% vto about 100%. Al-v though a wide range ofoperating temperatures are employed when utilizing-mineral acid cata--vlysts, the reaction is usually conducted at a relatively lowtemperature, that is, of the order of about F. to about 100 F.,preferably between about 35 F. and about 70 F.

The time of the reaction varies considerably but. in general, is in therange from about minutes to about 21/2 hours or longer depending uponre-l lated operating conditions. Usually the reaction time .is in therange from about to about 90 minutes.

The reaction may be carried out in the vapor lphase but is generallyconducted in the liquid phase. In a liquid phase operation, thepressures are at least suiilcient to keep the respective reactants fromvaprizing and are usually in the range from abouti to about 12atmospheres, al-y though pressures as high as 100 atmospheres may beemployed depending upon the reaction temperature, charge stock, andcatalyst employed.

Equal molecular quantities oi.' the isoparamn and mono-olen may be used.However, 'it has 30 been found that it is desirable tol maintain asubstantial excess of the tertiary hydrocarbon in the reaction zone 'andto operate in a reaction medium containing more than 5 volume percent ofthe catalystcomposition. For example, in an operation wherein isobutaneor isopentane is employed as the isoparaiiinic reactant, the mol ratioin fresh feed ranges from about 1 to as high as 30 mols and 'higher ofisoparafn per molof mono-oleflns present. v

Although various catalysts 'are employed Lin operations of thischaracter, a preferred catalyst comprises concentrated sulfuric acidhaving a concentration in the range from about 80% to about 100%. Inconventional alkylation operations employing a catalyst of this type,itis common practice to withdraw from the reaction zone at or near its topa single stream of acid-hydrocarbon reaction mixture. This mixture issubsequently splitlinto two streams, one stream being recycled to thereaction zone and the other being .discharged into a settler wherein theacid is separated from the hydrocarbon and the latter is segregatedforrecovery of the desired reaction product. This type `of operationisnot entirely satisfactory because the recycle emulsion stream lswithdrawn-from that zone.

in product quality results.

and the product emulsion stream are of the same composition, therebycausing the process to lack flexibility. We have now devised an improvedprocess in which, flexibility of control is obtained, and which, as aresult, achieves the production of greater quantities of the mostdesired hydrocarbon reaction-products.v

In accordance with our invention, the acid emulsion for recycling andthe acid emulsion from which the alkylate is recovered are withdrawn asseparate streams from the reaction zone. w

In a preferred modification of this invention, the acid emulsion forrecycling is withdrawn from the reaction zone at a point intermediatebetween the point where the reaction mixture enters and the point wherethe emulsion for product recovery Preferably, the reaction mixture isintroduced at or .near the bottom of the reaction zone, the acidemulsion for product recovery is discharged at or near the top of thereactor, and the emulsion recycle drawing the emulsion recycle streamfrom the reactor ataii intermediate point in this manner, greaterflexibility is' provided in the process. This type of operationappreciably reduces the amount of catalyst carried out into the settlingzone while maintaining a comparatively large amount of catalyst in theemulsion recycle stream. Usually the ratio of acid to hydrocarbonsin theemulsion recycle stream willybe from 1:2 to 2:1 whereas the ratio ofacid to hydrocarbons in the emulsion stream carried out into thesettling zone will be considerably lower, such as from 1:20 to 1:4.Thus, the handling of increased vquantities of hydrocarbon feed stock ispossible without the necessity of providing increased settler capacity,or, in the design of new equipment, a settler of reduced size will befound adequate. Means of improving the quality of thealky1ate product is`provided in this improved process inasmuch as greater quantities of theisoparaiflnic hydrocarbons can be charged to the reaction zone withoutrequiring increased settler capacity. Thus, increased ratios ofisoparafnic hydrocarbons are obtained in the reaction zone, andimprovement The process of our invention may be readily understood-byreference toy the vdrawing illustrating an embodiment of the same.

Referring specifically to the drawing, it is assumed for the purpose ofillustration that the hydrocarbon feed comprises a refinery butane cutcomprising butane, isobutane, isobutylene, alphabutylene, andbeta-butylene. The hydrocarbon feed is introduced into the system bymeans of line I and pump 2. As this feed flows through line I it isad'mixed'with recycled isobutane, initroduced by mans of line 3, andrecycled autorefrigeration condensate introduced by means of line 4,before being injected into the emulsion recycle stream 5 betweenemulsion recycle pump -6 and insulated reactor 8 I'he volume ratio ofmixers, mechanical agitators, or baiile plates.

The reaction mixture flows upwardly through reactor 8 with part of itdischarging through emulsion-for-recycle draw-oil line 5 and part of itdischarging through emulsion-for-product draw-off line I0. Thetemperature of the reaction mixture in reactor 8 is maintained at adesired level, usually in the range between 15 F. and 100 F., preferablyin the range between about F. and about '70 F. In general, the lower thetemperature of alkylation, the lower will be the acid consumption. Theheat of reaction is removed from the reaction mixture byautorefrigeration means which comprises evaporating part of thehydrocarbons in the reactor, removing them overhead through line I I,compressing them by means of compressor I2, condensing them by means ofcondenser I3, and

returning them to the bottom of the reactor a by means of pump I4, lines4 and 5, and jets 9. The refrigeration is distributed throughout reactor8 by withdrawing therefrom part of the acid hydrocarbon emulsion andrecycling it by means of liney 5 and pump 6 to the bottom of the reactorby means of jet 9. In accordance with this invention, theemulsion-for-recycle is withdrawn from' reactor 8 at a levelintermediate between the level at which the emulsion enters the reactorand the level at which the emulsion-for-product is discharged from thereactor. The emulsion-for-recycle draw-olf is preferably located atleast two feet below the level at which the emulsion-for-product iswith-V l drawn from the reactor.

The quantity of acid-hydrocarbon emulsion withdrawn from and recycled toreactor 8 by means of line 5 and pump 6 varies somewhat with thereaction time and the degree of distri- I may Vary in the range fromabout 1 to 2 to about 3 to 1. s

The emulsion-for-product recovery which is discharged from reactor 8through line I0 is passed to settlerl .I5 wherein the emulsion separatesinto two layers, an acid phase and a hydrocarbon phase. Underequilibrium conditions, the quantity of hydrocarbon in the emulsiondischarged into settler I5 is equivalent to approximately the quantityof hydrocarbon feed introduced mto the reaction system through lines Iand 3. 'The volume ratio of the acid to hydrocarbon in theemulsion-for-product stream discharging. into settler I5 varies with thequantity of emulsion recycled, the hydrocarbon feed rate and the depthin the reactor` at which the emulsion-for-recycle draw-off is locatedbelow the emulsion-forproduct draw-off. In general, this ratio variesbetween about l to l5 and l to 1 and is usually between about 1 to 9 and1 to 4.

The acid phase separating in settler I5 is withdrawn through line IB,with a small portion of it being discarded through line I'I and thebalance being recycled to the bottom of reactor 8 by means of line I8.The quantity of acid discarded from the system varies with theconditions of operation and is suilicient in quantity so that whenreplaced with approximately an equivalent amount of fresh make-up acidintroduced by means of line I9 the acid in the reaction mixture ismaintained at a strength of at least 80%, preferably ata strengthbetween 90% and 100%. v y

The hydrocarbon phase separated from the `emulsion discharged intosettler l comprises with a liquid that is to be cooled before thehydrocarbons are discharged into settler 24. In settler 24, anyentrained acid contained in the hydrocarbon phase is settled out andwithdrawn from the settler through line 25. The hydrocarbon mixturewithdrawn from settler 24 by meansV of line 26 is mixed with sodasolution introduced by means of line 21, and then passed throughincorporator l28 before being introduced into settler 29. For purpose ofdescription, it is assumed that the soda solution comprises an aqueoussolution of sodium hydroxide. However. any alkaline solution suitablefor the purpose may be employed; The soda solution separates from thehydrocarbon mixture in settler 29 and is withdrawn through line 30, asmall portion of it being discarded and the balance recycled to line 21by means of 4line 3|.l The soda washed hydrocarbons withdrawn fromsettler 20 by means of line 32 are mixed with water, introduced throughline 33, and then passed through incorporator 3i before being introducedinto settler 35. In settler 35 the water separates from thevhydrocarbons and is Withdrawn through line 36. A

The water washed hydrocarbons removed from settler 35 by means of line31 are charged vto distillation unit 38 wherein the butane's, lboth thenormal and the iso, are removed overhead through line 39, condensed incon-denser 40, and then introduced into distillation unit lil. Indistillation unit 4 l, the isobutane is separated from the normal butaneand is removed overhead through line 3 in which are located condenser42, pump 43 and li'eat exchanger M. After being liqueed in condenser 42,the isobutane is further cooled in heat exchanger M before beinginjected in the hydrocarbon feed line l whereby it is recycledv to thereaction zone.

withdrawn through line t5. The normal butane segregated in this mannermay be further treated or utilized in any desirable manner.

The residue withdrawn from distillation unit 38 by means of line 4Scomprises the desired reaction products and is commonly known as thetotal a1- kylate. This total alkylate is introduced into disnuation unit41 wherein the conditions of' temperature and pressure are adjusted soas to remove overhead by means of line 48 a hydrocarbon product having anal boiling point of about 290 The normal butane is removed .fromdistillation unit 4l as a residue whichris F. to about 320 F. and anoctane number in the range from about to about 96. This overhead streamis condensed in condensing zone 49 and is then withdrawn from the systemby means of line 50. The bottoms, product withdrawn by means of line`."I comprises a fuel boiling in the range from about 320 F. toabout500" F. and having an octane number in the range from about v'75 toabout 85. These reaction products may be further refined or handled inany manner desired.

The process of the present inventionmay be widely varied. It is to beunderstood that the respective zones may comprise any suitable numberand arrangement of units. It is also to be understood that indirect.cooling may be employed in a reaction Ain which an insulated reactionzone is utilized. In an operation of this character the reactionproducts are withdrawn from the top of the reaction zone while therecycled emulsion is withdrawn at an intermediate point from thereaction zone.

The invention essentially comprises withdrawing the recycle emulsionfrom a point intermediate the point at which the feed 4mixture isintroduced into the reaction zone and the alkylated product withdrawn.As pointed out heretofore conventional operating conditions may beemboron trifluoride, and phosphoric acid may be em- 4 ployed inthegprocess. Y

What we claim as new and wish to protect by Letters Patent is:

1. Process for reacting oleiins with isoparalns which comprises passinga feed mixture comprising olens, isopara'ins, and an alkylating catalystintogthe bottom of areaction zone, maln-l taining said reaction zoneunder alkylating conditlons, withdrawing fromA the upper section of saidreaction zone a stream containing alkylated products and the alkylatingcatalyst, separating the'catalyst and recovering the alkylated products,recycling said separated catalyst to the bottom 0f said reaction zone,withdrawing from an intermediate point of said reaction zone a catalystemulsion, and recycling said Icatalyst emulsion to the bottom of saidreaction zone with the fresh catalyst.

y 2. Process as defined by claim 1 in which said catalyst emulsionstream is recycled to the bottom of said reaction zone along with thefresh feed.

3. Process as defined by claim 1 in which said alkylating catalystcomprises concentrated sulfuric acid.

Y KARL OPRYSHEK.

J OI-IN N. CHATFIELD.

